The present invention relates to a building construction system and, more particularly, to a plank, post, and beam-type building system.
Plank, post and beam building systems have been in existence for many years. For example, the "log" home uses logs both vertically and horizontally to form wall and floor structures. Current building systems utilizing solid wood wall (hereinafter solid wall) construction techniques employ milled timbers with vertical, horizontal, or angular positioning for forming walls, floors and a roof. In all types of solid wood wall building construction, wood shrinkage causes a major design problem.
Wood shrinkage in a solid wall building allows the infiltration of elements such as wind, rain, heat, and cold, as well as infiltration of insects and vermin. Wood shrinkage also causes the structure to lose strength by allowing displacement of adjacent wood planks due to wind loading, earthquake, or other external forces. This displacement includes longitudinal or shear displacement of adjacent planks, referred to in the art as "racking."
To compensate for the loss of strength in a building due to wood shrinkage, additional structural members must often be added to the structure, which increases the costs and time of construction.
A partial cross section of the roof, wall, and floor of a typical, prior art solid wall building structure 10 is illustrated in FIG. 1. Horizontally laid floor planks 12 are nailed to a horizontally oriented floor plate 14 that is used to support the floor. The lower end of vertically oriented wall planks 16 are fastened to the outer surface of floor plate 14 and the upper end of the wall planks is fastened to the outer surface of a perimeter beam 20. The perimeter beam 20 is used to support a roof 22. A wedge 24 is placed atop the perimeter beam 20 to provide the correct angle or pitch of the roof.
As illustrated in FIGS. 2 and 3, prior art planks 16 used in the construction of solid wall houses use a tongue and groove configuration to prevent displacement of adjoining planks. It is to be noted that the tongue and groove structure does not prevent racking of adjacent planks other than by the frictional resistance between the surfaces of the tongue and groove. A prior art plank 16 includes a tongue 26 that extends outwardly from one side edge of the plank and a complementary shaped groove 28 formed in the opposite side surface of the plank to receive the tongue 26 from an abutting plank.
The problem caused by wood shrinkage is illustrated by comparing FIGS. 2 and 3. As shown in FIG. 2, when there is no wood shrinkage, the tongue 26 fits snugly within groove 28, thereby preventing displacement between adjoining planks 16. When planks 16 shrink, as shown in FIG. 3, gaps or spaces 32 appear between the tongue 26 and groove 28. These gaps 32 allow adjoining planks to move relative to one another, thereby reducing the strength of the building structure 10.
As stated above, the tongue and groove structure does not substantially prevent racking of adjoining planks. An attempt to avoid racking in prior art buildings is made by nailing the planks to underlying wood structure, such as the floor plate 14 or perimeter beam 20. However, due to the expansion and contraction of the wood planks from wood shrinkage and the resulting loosening of the nails, nailing the planks to underlying wood structures does not provide a completely satisfactory method of preventing longitudinal displacement.
Another commonly used feature in solid wall building construction is illustrated in FIGS. 2 and 3. The side surfaces of the wood planks 16 are chamfered for aesthetic purposes. The chamfers improve the appearance of the solid wall structures, however, a drawback of the V-shaped grooves 34 formed by the chamfers is that they provide entry points for the infiltration of elements and various insects and animals.
Accordingly, it is an object of the present invention to provide a plank-type building system that provides adequate strength for a solid wall structure without the use of additional strengthening elements.
It is another object of the present invention to provide a plank-type building system that prevents the infiltration of elements and insects while also accommodating the problem of wood shrinkage.